The United States Treasury says that in exactly one week, it won't have enough money to pay the government's bills.

We're not in this position because President Obama or the Secretary of the Treasury spent more than they were supposed to. And we're not in this position because investors refuse to buy our bonds.

We're in this position for one reason, and one reason only: because Congress told the government to spend more money than we have, and now Congress is threatening to run out on the bill. This isn't about new spending. This is about paying for the bills we've already run up.

The idea that we can renege on our debts without paying a high price is a fantasy -- a very dangerous fantasy.

Consider what happened in 2011, the last time the government came to the edge of a voluntary default.

Even the possibility that the government would not make good on its debts spooked investors and pushed up interest rates. According to experts, even talking about default cost the government $19 billion over 10 years.

And consumers and businesses got spooked too. The S&P index dropped by 17 percent. $800 billion dollars in retirement assets vanished. Mortgage rates went up nearly three-quarters of a point. The result was less consumer spending, fewer business investments, lower home ownership rates, and slower job growth.

That's what happened the last time Congress came to the edge of a voluntary default. What happens if we actually default?

Some economists estimate that the rise in interest rates will cost us $75 billion a year. Social Security checks and Medicare reimbursements will be delayed. People won't be able to pay their mortgages or small business loans. Interest rates will spike, and the credit market could freeze.

If we default on our debt, we could bring on a worldwide recession -- a recession that would pummel hard-working middle class people, people who lost homes and jobs and retirement savings and who are barely getting back on their feet.

I don't always see eye-to-eye with Wall Street CEOs, but on this one we agree: We can't run out on the bill and cause financial calamity for working families.

This fight is about financial responsibility. I can think of a lot of things we could do with $75 billion dollars. We could ramp up Meals on Wheels and Head Start. We could give students some relief on their loans. We could invest in more medical and scientific research. We could pay down the debt. But if we default on our loans, we've just flushed money down the drain. That's about as irresponsible as it gets.

For many things that we do in Congress, we can make a mistake, and then back up and fix it. A default on our national debt is not one of those things. If we default, this country will pay.

We are the United States of America. We always pay our debts -- in full and on time. That's who we are.

Elizabeth Warren was assistant to the president and a special adviser to the Treasury secretary on the Consumer Financial Protection Bureau. She single-handedly set us this bureau, putting in place the building blocks for an agency that will make (more...)